This invention relates to a process for making carbon black. In particular, it relates to a novel additive used for controlling the structure of carbon black produced by the furnace process.
The carbon black produced by an open flame decomposition of hydrocarbon materials usually has lower structure than that produced by an enclosed-direct-flame-decomposition method. The term "structure " describes the amount of linking of carbon particles to form chains or clusters. The fewer the number of chains or clusters, the lower is the structure of the carbon black. In some applications it is desirable to use carbon black having low structure. Consequently, for those applications carbon black produced by the open flame decomposition method (channel black) is preferred over that produced by the conventional direct flame decomposition method (furnace black). Since the process for producing channel black is much less efficient in terms of utilization of energy and hydrocarbon materials than the furnace process as the cost of both energy and hydrocarbon materials steadily increase, it becomes advantageous to modify the conventional furnace black process so as to produce carbon black having structure comparable with that of channel black.
To reduce the structure of furnace black, alkali metals in free or combined form are added to the hydrocarbon materials. The additive can be uniformly distributed throughout the hydrocarbon materials by suspending it in an aqueous solution or emulsion. A more detailed description of the modified furnace process can be found in U.S. Pat. Nos. 3,010,794, 3,010,795, 3,122,419, 3,347,633, 3,353,980, 3,607,064, and 2,564,700, which are incorporated herein by reference. The problem with this approach is that when the aqueous solution or emulsion is added to the hydrocarbon material the water flashes abruptly carrying with it into the precombustion zone droplets of oil and salts which deposit in the furnace, causing operating difficulties with the make oil nozzle, grit increase in the produced carbon black, etc. Prior systems have avoided this aqueous solution problem by using oil-soluble alkali metal organic compounds. The cost of these organic compounds makes their usage as additive uneconomical.
The present invention solves the problem inherent in the modified furnace process by forming a fine suspension of an alkali metal inorganic salt in oil which is added to the furnace.
Thus, one object of the present invention is to provide an improved process for the production of carbon black.
Another object of the invention is to provide a process for the production of furnace black which has a structure comparable to that of channel black.
A further object of the invention is to provide an improved method for incorporating reaction additives for reducing the structure of carbon black into hydrocarbon material from which carbon black is made.
Still another object of the invention is to provide a reaction additive for reducing the structure of carbon black produced by the furnace process.
A still further object of the invention is to eliminate the nozzle problems and grit formation problems in the furnace caused by flashing of water contained in the additive normally used for controlling the structure of furnace black.
Still another object of the invention is to provide a method for making a reaction additive used in the furnace process, which causes reduction of the structure of carbon black produced by that process.
A still further object of the invention is to use the amount of K.sub.2 CO.sub.3 in making the emulsion from which a reaction additive is made, which results in a maximum percentage of potassium in the additive.
Other objects of the invention will become apparent to those skilled in the art from a study of this disclosure and the appended claims.